How can I select from a derived table in Propel?

Question

I'm using v1.3 of the Propel PHP framework for an application, and I can't find a way to select from a derived table using the Criteria object. Part of the SQL I want is:

SELECT unioned_table.foo, quux.stuff, baz.more_stuff...
FROM
  quux
  INNER JOIN
  (SELECT foo, bar FROM table1 
    UNION
    SELECT foo, bar FROM table2
  ) AS unioned_table
   ON quux.field = unioned_table.foo
 INNER JOIN baz
   ON baz.blah = unioned_table.bar
 INNER JOIN ...
 WHERE conditions...

The actual SQL is more complex than this, but that just includes further joins.

I've tried to use Criteria::addAlias(), though unfortunately that tries to SQL-escape the table definition. I eventually gave up on trying to write the SQL in that manner, and created a view (called unisoned_table in this example).

I next tried to add joins to this table:

$c->addSelectColumn('unioned_table.foo');
$c->addSelectColumn(QuuxPeer::STUFF);
$c->addSelectColumn(BazPeer::MORE_STUFF);
// ...

$c->addJoin(QuuxPeer::FIELD, 'unioned_table.foo', Criteria::INNER_JOIN);
$c->addJoin(BazPeer::BLAH, 'unioned_table.bar', Criteria::INNER_JOIN);
// ...

$c->add(QuuxPeer::STUFF, $someval);
// ...

Sadly this results in the view being joined twice -- once as an inner join with qux, and once as a cross join with baz. Bizarrely, if I remove the baz SELECT column, then the cross join disappears.

Does anyone have any suggestions as to how I can do this? I can't use just bare custom SQL, as this Criteria may need to be modified (columns replaced, extra conditions added, etc) or used in a doCount() call.

DMI DMI · Accepted Answer · 2009-07-01T16:12:48

It turns out that order is important in Criteria::addJoin(); changing the joins so they read:

$c->addJoin(QuuxPeer::FIELD, 'unioned_table.foo', Criteria::INNER_JOIN);
$c->addJoin('unioned_table.bar', BazPeer::BLAH, Criteria::INNER_JOIN);

fixed the issue.

How can I select from a derived table in Propel?

1 Answers